Waterborne coatings are commonly applied to a wide variety of substrates, such as wood, metal, masonry, plaster, stucco, and plastic. In many of these applications the coating, which is based, upon an emulsion polymer, is exposed to wet environments caused by rain, dew, snow and other sources of water. The coating is exposed to water for prolonged periods of time in some applications. However, waterborne coatings especially clear aqueous coatings, tend to blush or whiten when exposed to water. Some prior arts had addressed this issue by using self-crosslinking approaches.
U.S. Pat. No. 4,267,091 disclosed the use of carbonyl groups containing monomers, water soluble aliphatic dihydrazide and metal salts such as zinc salt to improve water whitening (blushing).
U.S. Pat. No. 4,959,428 disclosed the use of a water soluble carbonyl containing copolymer as polymeric dispersant to make emulsion polymers to enhance anti-whitening.
U.S. Pat. No. 4,654,397, U.S. Pat. No. 5,447,970, U.S. Pat. No. 5,472,996, U.S. Pat. No. 6,117,936, U.S. Pat. No. 6,512,042, U.S. Pat. No. 6,515,042 and U.S. Pat. No. 6,538,062 disclosed the polymers with carbonyl containing monomers to enhance coating properties.
Some prior arts also taught the approaches to reduce water-whitening; however, they are not suitable for coating applications.
U.S. Pat. No. 6,515,042 B2 and U.S. Patent 2005/0245662 A1 disclosed styrene containing emulsion polymers with polymerizable surfactants for improving water-whitening resistance of pressure sensitive adhesives.
WO 2004/029172 disclosed the use of monomers containing aldehyde or ketone groups and polymerizable surfactants to enhance water whitening resistance for removable pressure sensitive adhesives.
None of the prior arts addressed the issue of early water blushing or whitening resistance for coating applications. There is currently a need for waterborne varnishes and water sealers having good early water blushing resistance, such as after two to four hours of dry time under normal conditions, to sustain unexpected rain, sprinkler water, or swimming pool water. None of the prior arts taught the disclosed polymer compositions for early water blushing resistance.
Waterborne coatings also frequently offer poor resistance to chemicals that are commonly used in homes and offices, such as gasoline, motor oil, brake fluid, transmission fluid, household cleaners, window cleaning fluids, antifreeze, and the like. The prior arts mentioned above have taught the use of carbonyl containing monomers to enhance resistance to chemicals. It is also desirable for such waterborne coatings to offer good adhesion to typical substrates and a high level of resistance to common chemicals. Such waterborne coating compositions would be of particular value for utilization in painting masonry structures, such as concrete, tile, or brick surfaces.